Winter 2012
Sky Report: Primary Schools
by Dr. Bob Doyle, Portable Planetarium Teacher

Resources for Primary School Teachers

• Primary School Sky Basics
  
  
• Winter 2012 Skies for Primary Grades
  

Winter 2012 Primary School Sky Basics

On a clear night, ½ of the universe is visible from your backyard! The night sky appears dark because space is mostly empty and the universe is expanding (growing in size). The night stars are distant suns that are much, much further away than our sun, our home star. The closest heavenly body to us is our moon, which goes around the Earth about every 4 weeks. With our eyes, we can see grey patches on the moon, which are huge lava plains that hardened and cooled in moon’s early history. As the moon orbits Earth, it is lit up by the sun. The moon has a day side and a night side, just like our Earth. When moon appears skinny, we are mainly seeing its night or dark side. When the moon appears full or nearly full, we are viewing mostly the moon’s day side. The nearest planets appear as bright, steady points of light. Mercury and Venus with their small orbits, always appear close to the sun, either in the eastern dawn or western dusk. The three outer planets that may be seen at any time of the night are Mars, Jupiter and Saturn.

At most about 1,000 stars can be seen on a dark, moonless night These stars are close by neighbors to our sun within our vast galaxy that has many more stars than the billions of people alive on Earth.

Winter 2012 Skies for Primary Grades

The most glorious sight in the evening sky in the winter months of 2012 is Venus, our nearest planetary neighbor. Look in the western sky as it begins to get dark, there you will see a tiny point of light. As it gets darker, Venus outshines all the night stars due to its closeness (to both Earth and sun) and highly reflective clouds. The planet Jupiter is not quite as bright as Venus but quite noticeable to the left of Venus in January and February. In mid March, these two brightest planets will appear close in the western dusk with the brighter Venus on the right. By the end of March, Jupiter will be lower than Venus. In March, the planet Mars will shine in the eastern evening sky.

The Big Dipper can be seen in the North Northeast on winter evenings. The four scoop stars are on top while the three handle stars are seen underneath. The two end stars of the scoop point left to the North Star. While the North Star is rather ordinary in appearance, it holds its position all through the night, every night of the year. For Earth's North Pole very nearly points to the North Star. So as the Earth spins, it causes our sun to appear to roll across the sky during the day while the stars, the moon and planets to move around the North Star at night.

The best and brightest evening star on view in the winter 2011 months is the star Sirius (sounds like serious), which is also the closest night star visible through the year. To be sure of recognizing Sirius, look in the southeast or southern evening sky for a group with three stars in a row, equally spaced and moderately bright. This is the belt of Orion, the brightest star group. In the mid evening skies of January (try 9 p.m.), make a line with Orion's belt stars and go down and to the left. There you will see a very bright star sparkling in all the colors of the rainbow. This is Sirius, a sun about two dozen times as powerful as our sun. Sirius is only 9 light years away so its light has taken that long to travel to the Earth. We are actually seeing Sirius as it shone 9 years ago, as it did in 2003. (2003 + 9 = 2012, our year). High above Orion is the bright golden star Capella (kah-PELL-ah), which is nearly overhead during the winter months. Capella's closeness to the North Star allows this bright star to be seen during the evening from fall through spring. Capella is also a relatively close star, being at a distance of 42 light years. Capella's golden light tells us that it's surface is cooler than our sun's (a yellow-white star).

During the 2012 winter months, the evening moon is about half full at the start of the month, growing to full about a week later. The full moon rises at sunset and shines all through the long winter nights. While the winter suns have a low sky path, the winter full moons have a high sky path, as if to make up for the sun being stingy with its light. In the middle of the winter months, the moon shines in the morning sky. Then late each month, the moon returns to the evening sky as a skinny crescent. The crescent moon will appear close to Venus on January 26^th, February 25^th and March 26^th. The evening moon will appear near the planet Jupiter on January 2^nd, January 29^th and 30^th, February 26^th and March 25^th. On March 7^th, the nearly full moon will appear near the planet Mars.

To learn more about the sky, consider visiting the Compton Science Center at Frostburg State University for our Sunday afternoon sky shows, starting in February at 4 p.m . Our new programs will start in room 224 and then visit the Science Discovery Center. Our February program is "Bears and their Skies". As our previous programs, we will first provide an informal tour of the current evening sky. (Free sky charts are available). Our March program is "Hooved Animals of Northern Lands and their Skies", held on March Sundays at 4 p.m.

For additional information, contact:

Dr. Robert Doyle, Planetarium Director
Frostburg State University
Department of Physics and Engineering
101 Braddock Road
Frostburg, MD 21532-1099
(301) 687-4270
rdoyle@frostburg.edu